The present invention relates generally to contactors for connecting electronic devices to circuit boards.
There are various methods of connecting an electronic device to a circuit board. However, when a device is under test, it is not desirable to permanently secure the device to the test circuit board. Therefore, a temporary contactor is often used. These contactors are widely available and have pads, spring loaded pads, pogo pins, leads, probes, or sockets, to make contact with the leads or input/output terminals of an electronic device.
FIG. 1 illustrates one conventional contactor 100. The contactor 100 is secured to a test circuit board 50. The electrical device 70 to be tested is then connected to the contactor 100. In actual operation, the electrical device 70 would be soldered or otherwise directly connected to a circuit board. However, soldering the electrical device 70 directly to the test circuit board 50 would be too time consuming and expensive, and removal might be destructive to the device 70. Therefore, the contactor 100 is used to provide the temporary electrical contact between the device 70 and the test circuit board 50.
The thickness 110 of the contactor 100 creates a test environment that does not otherwise occur in actual operation. For example, the electrical pathway 120 from the device lead 40 through the contactor 100, the test circuit board 50, back through the contactor 100, and to another device lead 41 is longer than the path would be if the device 70 was actually soldered to the circuit board. This causes inductance (between the device 70 and the circuit board 50) that is not present when the device is in use. For LNAs (low noise amplifiers), inductance on the emitter pin has been a historic problem with testing. Inductance interferes with the test for gain, third order intercept (the measure of the non-linearity of the amplifier), and noise figure (the ratio of the input-signal-to-noise ratio and the output-signal-to-noise ratio).
To account for the inductance, typical test methods employ a mathematical correction to compensate for the difference between test conditions and actual conditions. For example, for gain, the device will test lower than in actual use. Therefore, a mathematical correction for gain is applied. For third-order intercept, the device will typically test high. Therefore, another mathematical correction must be made. Because of the complex nature of various circuits, these mathematical corrections are not completely accurate.